Speedometers are, of course, standard equipment on automobiles, trucks, motorcycles, buses and most bicycles, as well as other vehicles. Conventional speedometers usually indicate the speed of the vehicle by the position of a needle on the dial of the speedometer. In many instances, the dial is lighted for better viewing, particularly at night. However, since the speedometer dial is positioned on the vehicle's instrument panel well below the direct line of sight needed by the driver when steering the vehicle, most drivers usually can spare only an occasional quick glance at the dial when maneuvering the vehicle. Such a glance is ordinarily given while the driver's main attention is elsewhere. Accordingly, although the speed at which the vehicle is traveling is ostensibly periodically monitored by the driver through his occasional glances at the dial, such glances usually leave little impression on the driver. Instead, the driver usually depends on the flow of traffic, road feel and other factors to guess the vehicle's speed. Such a practice can easily lead to habitually dangerously high vehicle speeds and increased risk of accidents, speeding citations and financial loss.
Conventional speedometers do not provide speed warnings to aid the driver in such circumstances as described above. A few specialized devices have been employed in conjunction with speedometers to give speed warnings. However, such devices are expensive and invariably require disassembly of the speedometer or the construction of a speedometer of special design and its substitution for the one with which the vehicle is equipped. Few of such devices have ever been used and none have been used extensively and successfully.
In the past, various U. S. patents have issued relating to various types of speedometers and related instrument faces. For example, U.S. Pat. No. 2,158,925, issued on May 16, 1939, to W. W. Braswell, teaches an indicator for a speedometer where color changes indicate higher speeds. The face of the speedometer is covered with patches of varying colors. A standard pointer is provided on the central axis of the instrument face so as to indicate the condition. Eventually, when the indicator moves into a different colored area, the operator will become aware of the fact that a particular condition will occur. This device does not utilize a wide instrument pointer which is capable of covering the bright colored area on the face.
U.S. Pat. No. 2,984,204, issued on May 16, 1961 to C. J. White, describes a rotating pointer that uses a cover for the dial to cause a "psychological" reaction. This indicator utilizes a triangular shaped pointer which moves along the face of the dial.
U.S. Pat. No. 2,951,462, issued on Sep. 6, 1960 to E. G. M. Wilkes et. al., describes a rotating cover for a speedometer that reveals color changes at certain speeds. This device utilizes a conventional pointer. This device only utilizes a colored zone of increasing width that is provided around the periphery of the instrument face.
U.S. Pat. No. 3,980,041, issued on Sep. 14, 1976 to R. B. Evans, describes a speedometer with a speed warning indicator. In particular, this device utilizes a transparent plate, such as a transparent decal, having an attached transparent plastic sheet bearing adhesive for attaching it to the transparent face cover of the speedometer. The plate bears indicia, such as color and/or a plurality of spaced lines, demarking the plate and the speedometer dial viewed through the plate. As a result, it indicates a speed warning on the dial while still permitting unobstructed viewing of all of the dial.
It is an object of the present invention to provide an instrument display which gives an immediate warning signal to the operator of the vehicle when a limit has been exceeded.
It is another object of the present invention to provide an instrument face in which the pointer itself serves to expose the warning indicia.
It is a further object of the present invention to provide an instrument face which will change shape as the warning zone continues to be uncovered by the pointer.
It is still a further object of the present invention to provide an instrument display which is easy to use, relatively inexpensive and easy to manufacture.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.